The present invention relates to surgical devices made from polymers of p-dioxanone and more particularly to molded surgical devices of such polymers having improved in vivo performance characteristics.
It is well known that in many and various surgical procedures synthetic devices, that is, devices made from foreign materials, are very often implanted. Examples of such procedures are in surgery wherein tantalum or stainless steel or other metal clips are used to control bleeding by ligating various blood vessels or other tubular organs during the surgical procedure. Furthermore, in other surgical procedures, various other fasteners, staples or clips are implanted for various fastening support or other reasons during a surgical procedure. In most instances, these devices remain in the patient for considerable periods of time, though in some instances, they may be removed at some later date or even rejected by the natural physiological function of the human body.
For the most part these metal surgical devices, even though they may cause no harm from the medical viewpoint, it is desired they not be allowed to remain in the body as they greatly disrupt the post-operative x-ray procedures and subsequent diagnostic imaging of the patient. The metal materials not only disrupt X-ray imaging, but they also disrupt the newer computerized axial tomography imaging, and other of the new types of diagnostic imaging procedures. Hence, it is desirous that the surgical devices be replaced by non-metallic, bio-compatible materials which do not have a disruptive effect on the new diagnostic imaging procedures. It is even more desirable to make the medical devices, in many instances, out of absorbable polymers so that once they have completed the desired function, they are absorbed by the human body, and, hence, have no subsequent effect on diagnostic imaging or the like. Devices made from absorbable polymers also prevent any long term complications which might arise from having a foreign body present in the tissue.
Surgical devices and the desired absorbable polymers are more fully disclosed in U.S. Pat. No. 4,052,988 issued Oct. 11, 1977 and incorporated herein by reference. A specific process for making such a desirable surgical device made from these absorbable polymers is disclosed in co-pending commonly assigned patent application Ser. No. 288,275, filed July 30, 1981. In that case, there is described a process of producing a molded surgical device from polymers of p-dioxanone. Though surgical devices produced in accordance with the method described in the above mentioned patent application have desired strength and other properties for many surgical procedures, it is still important to even further improve the strength, functional integrity, flexibility, and especially the tactile and audible properties of surgical devices made from these polymers. These improved properties expands the potential usage of the devices and improves their reliability, stability and the in vivo performance of such surgical devices.
Many surgical devices used in various procedures start in one position, i.e., an open position, and when in the proper place are put in a second position; i.e., a closed position. For example, a hemostatic clip is placed about a vessel to be closed with the clip in an open position. Once the clip is properly placed, the clip is closed to shut off the vessel. Many of these devices which have their position modified during use are used in areas where visibility may be a problem and the surgeon must rely on other senses such as feeling and hearing in order to properly place the device. Hence, it is often desired that such devices have both tactile and audible properties to assist the surgeon when using the device. Tactile properties are placed in the device by providing some resilient portion in the device; i.e., a portion which resists the movement of the device from one position to another position. For example, in a hemostatic clip the resilient portion may be a hinge which holds the clip in an open position and which resiliency must be overcome to close the clip, thus providing the user with some tactile " feedback" as the clip is closed. Audible properties may result from some interlocking or interengaging of parts once the device is placed in a desired position, i.e., the parts snap together with a sound that can be heard by the user to let the user know the device has been placed in the desired position.
Also, in U.S. Pat. No. 4,025,988 there is described an annealing procedure useful for sutures to improve desirable properties of the sutures. The suture to be annealed is an oriented filament. The oriented filament is held under restraint while being annealed and the molecular configuration of the oriented product altered to improve the desired strength properties of the suture.